The present invention relates to so called drill pipe protectors and, particularly, to a protector which is designed to provide a fluid tight hydraulic seal between the drill pipe and the protector.
Drill pipe protectors are well known. Generally they are formed of an elongated annular body of an elastomer which encases a metal band as a backing element. Drill pipe protectors are used in combination mounted at spaced locations on the drill pipe where they function as a bushing to prevent the drill pipe from colliding with the well bore or casing. First, there is a tendency for the protectors to slip on the drill pipe. They are sized such that the fluids used during the drilling operation can pass up along the protector and out of the well. In many cases a plurality of longitudinal flutes which extend radially from the outside surface of the protector body and provide wear-resistant, contact surfaces between the drill pipe and the well are formed on the protector and channel the drilling fluids around the protector. Some drill pipe protectors are fixed to the drill string and are adapted to rotate with the drill pipe during the drilling operation whereas others are non-rotating protectors and float on the drill pipe. The present invention is directed to the former non-floating protector.
There are numerous examples of drill pipe protectors in the prior art some of which are shown in U.S. Pat. Nos. 2,959,453; 3,103,391; 3,197,262; 3,227,498; 3,320,004; 3,410,613; 3,414,337; 3,894,780; 4,011,918; 4,105,262; and 4,266,578. U.S. Pat. No. 4,266,578 illustrates a protector having many of the features found in prior protectors viz. a fluted, elongated, elastomeric body encasing a metal reinforcing band formed by two semi-cylindrical halves hinged at one side and locked with a tapered pin at the other, wherein the elastomeric body is a composite of an abrasion resistant rubber on the well wall engaging face and a low compression rubber interfacing the drill pipe.
While prior drill pipe protectors have been effective there have been some drawbacks with their use. Due to this slippage, often the protectors are found accumulated on one portion of drill strip, e.g., accumulated above a tool joint, after the drilling operation.
In addition to slippage, another disadvantage of prior drill pipe protectors which is associated with slippage is that the drilling mud seeps between the drill pipe and the protector leading to some corrosion of the pipe.
Thus, there is a need for a drill pipe protector with improved engagement with the drill pipe.